1. Field of the Invention
The invention relates to a signal converter, and more particularly, to a signal converter with only one ADC (analog to digital converter) in a radio frequency receiver.
2. Description of the Related Art
In wireless communication systems, information is transmitted over radio frequency (RF) communication channels that are established between terminals. Each terminal includes radio frequency receiver circuitry used to select signals of a desired communication channel, to down convert the selected radio frequency signals to baseband digital signals for further digital signal processing.
In the RF receiver, frequency down conversion may be designed by a number of different technologies, wherein the most popular are direct conversion and intermediate frequency (IF) conversion technologies. In a direct conversion RF receiver, also called a zero-IF receiver, the signal of interest is converted directly to a zero frequency carrier. In a low IF RF receiver, the signal of interest is converted to an intermediate frequency carrier near the zero frequency. Additionally, super-heterodyne is also a well known technology to convert an RF signal to a baseband digital signal via several intermediate stages.
Once the signal of interest is converted to a baseband signal or low-IF signal, digitalization will then be performed to convert the analog signal into digital signals. Next, the digital signals will be further processed for channel filtering, channel estimating, the signal demodulating, the signal decoding, quality estimating and so on.
Usually, for a communication system with data transmitted by inphase (I) and quadrature phase (Q) signal components, two ADCs are required for each of the inphase signal component and the quadrature phase signal component to sample the analog I and Q phase component into digital format. However, the use of two ADCs requires more die area, more die cost, and more power consumption. Thus, a novel RF receiver architecture with a more efficient hardware design should be provided.